"Alma Eyre (Sonata Software North America)" <v-aleyre@xxxxxxxxxxxxx> writes: > Hello, > > This is Alma supporting Azure for Japanese customers. I had a question from a customer that I could not find the answers for. I saw this github(https://github.com/torvalds/linux/commit/88c9281a9fba67636ab26c1fd6afbc78a632374f) page, and I was > wondering if someone on this list might be able to answer the question. > > Will the name of hyperv_clocksource_tsc_page or hyperv_clocksource pages change? > > Background: > > The customer is experiencing "tsc: Fast TSC calibration failed" error > on their CentOS 7.4（3.10.0-693.11.6.el7) VM. Hi Alma, I think the following upstream commit would help: commit 71c2a2d0a81f096a2932fccb39a500116fece554 Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Date: Thu Jun 22 18:07:30 2017 +0800 x86/hyperv: Read TSC frequency from a synthetic MSR > > My research: > > Although I could find information that both of these pages are maintained by Microsoft, I could not find any information about whether these pages are subject to name change. > > Regarding both > > Here(https://github.com/torvalds/linux/commit/88c9281a9fba67636ab26c1fd6afbc78a632374f) it says "On Hyper-V platform there > > are two good clocksources: MSR-based hyperv_clocksource and > > recently introduced TSC page." > > Regarding hyperv_clocksource_tsc_page > > The mechanism is detailed here(https://opensource.com/article/17/6/timekeeping-linux-vms) but whether or not this page will ever change names is not noted. It also says "Microsoft reinvented the pv_clock protocol with their own TSC page proctol, " > > Here(https://lists.linuxfoundation.org/pipermail/virtualization/2017-February/034235.html) it says that the TSC page is documented, but I cannot find the documentation. > TSC page clocksource is documented in TLFS: https://github.com/Microsoft/Virtualization-Documentation/raw/master/tlfs/Hypervisor%20Top%20Level%20Functional%20Specification%20v5.0b.pdf (12.6.2 Format of the Reference TSC Page) But to be honest I didn't get your question. In case you're asking if 'hyperv_clocksource_tsc_page' name is stable than the answer is: there is no guarantee. Nobody will probably change the name just for the sake of change but it can be changed for a reason. -- Vitaly _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
